1. Technical Field
The present disclosure relates to a chemical vapor deposition (CVD) apparatus for depositing compound semiconductors and to a method for manufacturing compound semiconductor epitaxial substrates such as of, for example, silicon carbide semiconductors.
2. Description of the Related Art
Wide bandgap semiconductors are used in various semiconductor devices such as power devices (power elements), environment resistant devices, high-temperature devices and high-frequency devices. In particular, the application of attention is to power devices such as switching devices and rectifying devices.
Of the wide bandgap semiconductors, silicon carbide (SiC) is relatively easy to form into substrates. Further, the thermal oxidation of this semiconductor material gives silicon dioxide (SiO2) films that are good gate insulators. These benefits make SiC attractive for use in the development of power devices (see, for example, Japanese Unexamined Patent Application Publication No. 2012-151400).
Some of the typical switching devices using SiC are metal insulator semiconductor field effect transistors (hereinafter, “MISFET”) and metal semiconductor field effect transistors (hereinafter, “MESFET”).
SiC crystals are generally grown by a CVD method. For example, Japanese Unexamined Patent Application Publication No. 5-001380, Japanese Unexamined Patent Application Publication (Translation of PCT Application) No. 2003-507319, and Materials Science Forum Vols. 389-393 (2002) pp. 187-190 disclose methods for forming SiC epitaxial layers on substrates using a hot-wall CVD apparatus. Further, Materials Science Forum Vols. 389-393 (2002) pp. 187-190, and Japanese Unexamined Patent Application Publication (Translation of PCT Application) No. 2003-507319 propose that SiC is epitaxially grown while rotating the substrate in order to enhance the uniformity of the SiC epitaxial layer.